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A281856 One fourth of the order of the abelian non-cyclic groups (Z/A033949(n)*Z)^x. 2
1, 1, 2, 2, 2, 3, 2, 3, 2, 4, 5, 6, 3, 6, 4, 3, 5, 6, 4, 8, 6, 10, 6, 9, 4, 9, 8, 12, 5, 8, 11, 6, 6, 10, 9, 15, 6, 8, 6, 16, 14, 10, 6, 18, 11, 15, 18, 8, 15, 10, 8, 12, 12, 9, 10, 18, 12, 9, 22, 14, 18, 24, 8, 20 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

a(n) is one fourth of the row product of the irregular triangle A281854.

LINKS

Table of n, a(n) for n=1..64.

FORMULA

a(n) = A000010(A033949(n))/4, n >= 1.

MATHEMATICA

EulerPhi@ Select[Range[2, 130], ! IntegerQ@ PrimitiveRoot@ # &]/4 (* Michael De Vlieger, Feb 02 2017 *)

CROSSREFS

Cf. A000010, A033949, A060679, A281854.

Sequence in context: A029235 A289052 A329046 * A106696 A131839 A143299

Adjacent sequences:  A281853 A281854 A281855 * A281857 A281858 A281859

KEYWORD

nonn

AUTHOR

Wolfdieter Lang, Feb 02 2017

STATUS

approved

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Last modified June 20 00:16 EDT 2021. Contains 345154 sequences. (Running on oeis4.)